Molding system with integrated film heaters and sensors

ABSTRACT

Film heater apparatus and method for heating a melt channel in a molding device includes structure and/or steps whereby a first dielectric layer is disposed on a surface of a substrate. An active heating element is disposed on the first dielectric layer, the active heating element being configured to generate heat to heat the melt channel. The active heating element has contact terminals arranged to support an electrical connection to the active heating element. A second dielectric layer is disposed over the active heating element, but not covering the contact terminals, thereby permitting coupling of the heater element to an electrical supply.

[0001] This application is a continuation of U.S. patent applicationSer. No. 10/454,501, filed Jun. 5, 2003 (allowed), which is acontinuation of U.S. patent application Ser. No. 10/187,331, filed Jun.2, 2003, now U.S. Pat. No. 6,575,729, which is a continuation of U.S.patent application Ser. No. 09/695,017, filed Oct. 25, 2000, nowabandoned, which is a continuation of U.S. patent application Ser. No.09/550,639, filed Apr. 14, 2000, now U.S. Pat. No. 6,341,954, which is acontinuation of U.S. patent application Ser. No. 09/096,388, filed Jun.12, 1998, now U.S. Pat. No. 6,305,923, all of which are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an improvement in heatmanagement and process control for a molding process and, moreparticularly, to the use of active and/or passive film heating and/orsensing elements located along a flow channel of molten resin to a moldcavity space.

[0004] 2. Description of the Related Art

[0005] In an injection molding process, it is important to maintain aresin in a molten state as it flows from a nozzle of an injectionmolding machine, through a mold sprue bushing, a mold manifold, a hotrunner nozzle, and into a mold cavity space, where the resin cools toform an injection-molded article. Additionally, the shear stress profileof the flow of resin must be monitored and managed to insure properfilling of the cavity space. This is especially important in the areaclose to the mold gate because the temperature there is rapidly cycledbetween hot and cold conditions before the molded article is removedfrom the cavity. Temperature control issues are also very important whenmolding certain thermally-sensitive materials such as PET in amulticavity mold or when molding articles made of different materialsthat are injected through a single hot runner nozzle. Accordingly, mucheffort has been directed towards improving heat management and processcontrol in the injection molding process, particularly in the moldmanifold and hot runner nozzle. To date, several methods and means havebeen employed with varying degrees of success. Included among themethods and means commonly employed are heat pipes, high frequencyinduction heaters, microwave heaters, ceramic heaters, infraredradiation heaters, electrical heaters, etc. Such electric heatersinclude coils, band, or cartridge heaters which are used to heat themolten resin inside the screw barrel, in the machine nozzle, in themanifold, in the hot runner nozzle, and in the mold gate area.

[0006] U.S. Pat. No. 5,645,867 issued to Crank, et al. (incorporatedherein by reference) illustrates the current state of the art withrespect to heating the mold manifold. Crank, et al. teaches heating themanifold by disposing infrared radiation heaters on an outer surface ofthe manifold. However, as is typical of such prior art manifold heatingapparatuses, a significant proportion of the heat generated by theheaters is wasted heating the entire manifold block rather than directlyheating the resin flowing in a melt channel contained therein.

[0007] U.S. Pat. No. 5,614,233 issued to Gellert (incorporated herein byreference) discloses a state of the art heater for a hot runner nozzle,in which a helical electrical heater is embedded in a spiral groove thatsurrounds the hot runner nozzle. The heater comprises a resistive wireenclosed in a refractory powder electrical insulating material such asmagnesium powder oxide. The helical portion of the heater ispress-fitted and reshaped into place in the spiral groove. However, thedisclosed heater heats both the hot runner nozzle body and the meltchannel contained therein, a relatively inefficient heating arrangement.Additionally, manufacturing the spiral groove and assembling the heatertherein is time-consuming and costly.

[0008] The foregoing problems with prior art heaters are particularlyevident in coinjection and multiinjection mold manifolds and hot runnernozzles. For example, U.S. Pat. No. 4,863,665 issued to Schad, et al.(incorporated herein by reference) discloses the use of a singleelectrical heater attached to the outer surface of a hot runner nozzleto heat three melt channels simultaneously. Schad, et al., however,faces several drawbacks. First, less heat is transmitted to the innerchannels than to the outer channels. Second, the heat supplied to eachchannel cannot be varied according to the size of each channel and therheological characteristics of the resin flowing therein.

[0009] European Patent 312 029 B1 issued to Hiroyoshi (incorporatedherein by reference) discloses a heater made of an insulating ceramicfilm that is flame-sprayed on the outer surface of the nozzle whichintroduces the resin into the molding machine. The heater may be acontinuous area heater completely covering the nozzle, a heater made ofa plurality of longitudinal strips, a thin film heater made of helicalstrips, or a two piece independent heater with more power supplied tothe nozzle where it contacts the mold. However, the heater disclosed inHiroyoshi has several significant drawbacks that militate against itsapplication to a mold manifold or hot runner nozzle. First, theHiroyoshi heater is not removable and thus requires replacement of theentire element when the heater burns out. Second, the heaterinefficiently heats the entire machine nozzle body rather than directlyheating the molten resin. Third, the heater cannot provide a profiledtemperature gradient across the flow of molten resin, an importantfeature for managing shear stress in the flow of molten resin. Finally,the thickness of the disclosed heater is 0.5 to 2 mm, which isacceptable for application to the outer surface of the machine nozzle,but intolerable for application to the interior of a melt channel in amold manifold or hot runner nozzle.

[0010] U.S. Pat. Nos. 5,007,818 and 5,705,793 disclose the use ofheaters which are deposited directly on the flat surface of the cavitymold. U.S. Pat. No. 5,504,304 discloses a removable ceramic heater madeof a ceramic paste whose thickness is hard to control. Such heaters asthese do not provide for intimate contact with the nozzle body or thenozzle tip and thus reduce heat transfer and increase heat loss.Reference also made be had to the following U.S. patent (each of whichis incorporated herein by reference) which disclose heater technology;U.S. Pat. Nos. 5,155,340; 5,488,350; 4,724,304; 5,573,692; 5,569,398;4,739,657; 4,882,203; 4,999,049; and 5,340,702.

[0011] Accordingly, there is a need in the art for a method and means ofheating a melt channel of a mold manifold and hot runner nozzle in amanner that is efficient in terms of energy, space, and location.

[0012] There is an additional need in the art for an efficient methodand means of providing an appropriate amount of heat to each meltchannel in a coinjection or multiinjection hot runner nozzle based onthe localized size and shape of each melt channel and the rheologicalcharacteristics of the resin flowing therein.

SUMMARY OF THE INVENTION

[0013] It is an object of the present invention to provide method andapparatus for efficient heat and flow management of molten resin withinthe melt channel of a mold manifold and a hot runner nozzle.

[0014] According to one aspect of the present invention, apparatus usedin conjunction with an injection molding machine includes a cavityplate, a core plate disposed relative to the cavity plate to define acavity space, and a manifold having formed therein an inlet passage forreceiving a flow of molten resin from a nozzle of the injection moldingmachine. A hot runner nozzle is also provided for directing the flow ofmolten resin from the manifold inlet passage to the cavity space. A moldgate is also provided for regulating the flow of molten resin from thehot runner nozzle to the cavity space, the mold gate together with thehot runner nozzle and the manifold inlet passage defining a non-flatmelt channel for directing the flow of molten resin from the nozzle ofthe injection molding machine to the cavity space. An active or passivethin film element is disposed along the non-flat melt channel.Preferably, the thin film element is an active heater in contact withthe molten resin.

[0015] According to another aspect of the present invention, apparatusused in conjunction with an injection molding machine includes a molddefining a cavity space, and a manifold having formed therein an inletpassage for flow communication with a nozzle of the injection moldingmachine. A hot runner nozzle is provided for flow communication witheach of the cavity space and the manifold inlet passage, the hot runnernozzle and the manifold inlet passage together defining a melt channel.A plurality of active or passive thin film elements are intermittentlydisposed along the melt channel.

[0016] According to a further aspect of the present invention, apparatusfor directing a flow of molten resin from a nozzle of an injectionmolding machine to a cavity space defined by a mold includes a manifoldhaving formed therein an inlet passage for receiving the flow of moltenresin from the nozzle of the injection molding machine. A hot runnernozzle is provided for directing the flow of molten resin from themanifold inlet passage to the cavity space, the hot runner injectionchannel and manifold inlet passage together defining a melt channel. Anactive or passive thin film element is disposed within the melt channel.

[0017] According to yet a further aspect of the present invention,apparatus for directing a flow of molten resin supplied by an injectionmolding machine to a cavity space defined by a mold includes a hotrunner nozzle having a plurality of melt channels for directing the flowof molten resin supplied by the injection molding machine to the cavityspace. A plurality of active/passive thin film elements is disposedsubstantially adjacent to each melt channel for supplying heat to theflow of molten resin within that melt channel.

[0018] Yet a further aspect of the present invention includes apparatusto be used in conjunction with an injection molding machine. A cavityplate is provided, and a core plate is disposed relative to the cavityplate to define a cavity space. A hot runner nozzle is provided andincludes a plurality of melt channels, each melt channel directing oneof multiple flows of molten resin supplied by the injection moldingmachine to the cavity space. An active or passive thin film element isdisposed along each melt channel.

[0019] According to a further aspect of the present invention, a methodof injection molding includes the steps of injecting molten resin into amelt channel defined by a manifold and a hot runner nozzle, anddisposing an active or passive thin film element along the melt channelfor heating the molten resin.

[0020] These and other objects, features, and advantages can be betterappreciated with reference to the following drawings, in which likereference numerals refer to like elements throughout.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention is described in conjunction with theaccompanying drawings, in which:

[0022]FIG. 1(a) is an axial cross sectional view of a circular meltchannel of a mold manifold;

[0023]FIG. 1(b) is a longitudinal cross sectional view of the meltchannel of FIG. 1(a) schematically depicting the velocity profile of theresin as it flows through the melt channel;

[0024]FIG. 1(c) is a longitudinal cross sectional view of the meltchannel of FIG. 1(a) schematically depicting the shear stress profile ofthe resin as it flows through the melt channel;

[0025]FIG. 1(d) is a cross sectional view of a manifold, including anetwork of melt channels, schematically depicting variations in theshear stress profile of the resin as it flows through the manifold;

[0026]FIG. 2(a) is a graph showing the relation between temperature andviscosity at a constant shear rate;

[0027]FIG. 2(b) is a graph showing the relation between shear rate andviscosity at a constant temperature;

[0028]FIG. 2(c) is a longitudinal cross sectional view of a melt channelshowing the velocity of a flow of resin as it rounds a corner in themelt channel;

[0029]FIG. 2(d) is a longitudinal cross sectional view of a melt channelshowing boundary layers formed therein by a flow of resin;

[0030]FIG. 3 is an elevated perspective view of a mold manifold showinga plurality of 90 degree turns;

[0031]FIG. 4(a) is a schematic representation of a mold manifold;

[0032]FIG. 4(b) is a series of axial cross sectional views of the moldmanifold of FIG. 4(a) showing uneven formation and distribution ofboundary layers;

[0033]FIG. 5 is a longitudinal cross sectional view of a three-material,five-layer PET preform showing incomplete penetration of one of thelayers, a phenomenon known as DIP;

[0034]FIG. 6 is a schematic cross section of a high cavitation moldcomprising thin film manifold and hot runner heaters in accordance withan embodiment of the present invention;

[0035]FIG. 7(a) is a schematic cross section showing the layers of thinfilm elements in film heater 62 of FIG. 6;

[0036]FIG. 7(b) is a schematic cross section showing the layers of thinfilm elements in film heater 65 of FIG. 6;

[0037]FIG. 8(a) is a cross sectional view of an improved hot runnernozzle design in accordance with another embodiment of the presentinvention;

[0038]FIG. 8(b) is a chart showing the lack of temperature drop in theupper portion of the hot runner nozzle;

[0039]FIG. 9 is a cross sectional view of an improved nozzle tip andmold gate insert dance with an yet another embodiment of the presentinvention;

[0040]FIG. 10 is a schematic cross sectional view of the nozzle tipshown in FIG. 9;

[0041]FIG. 11 is a cross section of the components of the FIG. 9 nozzle;

[0042]FIG. 12 is a cross sectional view of a coinjection nozzlecomprising thin film heaters in accordance with another embodiment ofthe present invention;

[0043]FIG. 13 is a cross sectional view of a molding machine includingshooting pots and comprising thin film elements within the shooting pot;

[0044]FIG. 14(a) is an axial cross sectional view of a melt channelhaving a thin film heater removably attached to its outer periphery;

[0045]FIG. 14(b) is an axial cross sectional view of a melt channelhaving a thin film heater removably attached to its inner periphery;

[0046]FIG. 15 is a schematic cross sectional view of a molding machinehaving both a valve gate and a thermal gate;

[0047]FIG. 16(a) is a schematic cross section of a valve-gated nozzlehaving a thin film heater;

[0048]FIG. 16(b) is a schematic view of the thermocouple on the end ofthe valve stem of FIG. 16(a);

[0049]FIG. 17 is a schematic cross section of the film heater of FIG.16(a);

[0050]FIG. 18(a) is a schematic cross section of a nozzle tip havinginternal and external film heaters;

[0051]FIG. 18(b) is an end view of the film heater on the tip of thenozzle of FIG. 18(a);

[0052]FIG. 19(a) is a schematic cross section of a nozzle plug having aninternal film heater;

[0053]FIG. 19(b) is a schematic cross section of a nozzle plug having anexternal film heater;

[0054]FIG. 20 is a schematic cross section of a manifold and nozzlewhich have film heaters;

[0055]FIG. 21(a) is a schematic cross section of a mold gate inserthaving a film heater;

[0056]FIG. 21(b) is a schematic cross section of a mold gate sleevehaving a film heater;

[0057]FIG. 22 is a schematic cross section of a mold plug having a filmheater with different widths;

[0058]FIG. 23(a) is a schematic view of the resistive patterns on a thinfilm heater:

[0059]FIG. 23(b) is a schematic view of the resistive patterns onanother film heater;

[0060]FIG. 23(c) shows a film heater disposed inside a melt channel; and

[0061]FIG. 23(d) shows a film heater disposed on the outside of a meltchannel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 1. INTRODUCTION

[0062] The advantageous features of the present invention will bedescribed with respect to a plastic injection molding machine utilizingthin film heater and sensor technology. Of course, the invention is notlimited to such embodiments, but may be applied in any moldingtechnology within the scope of the attached claims.

[0063] As described below, an injection molding system according to thepresent invention may include electrical heaters and temperature sensorsto better manage and control the flow of the molten resin between in theinjection machine nozzle and the mold cavity space. Thus, the presentinvention may comprise active and/or passive film elements which may bedeposited directly on the surface of the mold elements (such as in themanifold and/or adjacent the mold gate area) to precisely manage thetemperature profile in the moving, molten resin. For some applications,these film elements may be deposited directly on the nozzle housingand/or the nozzle tip, on a runnerless probe, on a valve stem, or on asurface of a mold gate insert. In other cases, the film elements may bedeposited on a removable heater plug which is located at one or morepredetermined positions in the molding system. Preferably, the activefilm element comprises a film heater, and the passive film elementcomprises a thermal sensor (e.g., a thermistor or thermal couple) and/ora pressure sensor. The film elements may be single layer elements, butpreferably comprise a sandwich of several film layers having differentelectrical, thermal, and wear characteristics. One film layer willusually be made of an electrically highly-resistive material. Dependingupon the particular molten-resin and the particular molding processcharacteristics, the film can be either a “thin” or “thick” elementwhich is preferably deposited using chemical deposition, vapordeposition, film spray techniques, or equivalents thereof. The filmheating and sensing elements may also comprise flexible substrates whichare trimmed and installed, as needed, at any location in the injectionmolding machine.

[0064] Also within the scope of the present invention is the use of suchfilm elements in conjunction with the known heaters described above. Bycarefully selecting the appropriate film heating elements (when used inconjunction with or in place of known heaters) fine adjustments may bemade to the molten resin temperature gradient and profile to provideprecise heat flow control. Such precise control can be effected beforethe molten resin enters the heated space, thus providing constant (orprecisely-managed) viscosity and velocity of the melt flow.

[0065] If the film heater is directly deposited, this can also eliminatethe air gap between the heater and the heated surface thus providingintimate and direct contact for improved temperature transfer betweenthe heater and the heated surface, to achieve energy savings and longerheater life. Also, the direct deposition of the film heater makes themold elements themselves simpler to design and manufacture since theymay be made smaller and more energy efficient and use less space withinthe mold machine itself. Furthermore, the quality of the molded articlesis significantly improved because of the precise management of the heatflow in the injection molding machine. Additionally, when molding anarticle that has several resin layers deposited at once, the use of filmheater elements will allow each layer to having a uniform thickness andlength. In the case of molding PET preforms using the film heatersdescribed below, the acetaldehyde level is lower and is more uniformlydistributed across the cavities of the multi-cavity mold. This isbecause the film heaters are located adjacent the melt channels and canbe individually controlled and activated so that the temperature is veryuniform across the entire manifold.

[0066] Also, by improving the heating control at the mold gate area, thesprue gate (vestige) of the molded preform may be made very small withsubstantially no crystallinity penetrating the preform wall.

[0067] Further, the use of the film heaters according to the presentinvention will provide significant advantages when molding two differentcolor resins through the same nozzle. Precise heat control will allow anabrupt transition between the different colors, increasing the qualityof the final product and reducing wastage.

[0068] Thus, the film heaters according to the present invention are inintimate contact with the surface to be heated, and can provide fasterheating response time, lower temperature inertia, are small enough to beplaced in many different areas of the mold, and can provide a tightlyconstrained temperature profile which leads to faster molding, higherquality in the produced articles, smaller machine parts, reduced energyconsumption, and longer machine life.

[0069] By utilizing film sensors according to the present invention,more precise temperature management and control of the entire processcan be achieved. Such film sensors can be placed in many more locationsthan known thermal couples, and are easily installed, maintained, andmonitored. Therefore, process feedback and control is also enhancedaccording to the film sensors of the present invention.

2. PREFERRED EMBODIMENTS OF THE PRESENT INVENTION

[0070] The present embodiments locate compact active and/or passive filmelements along a melt channel from, for example, a sprue bushing to amold cavity space to improve heat and flow management therein. Theactive elements, which may be fabricated using advanced thin filmtechnologies, are compact, reliable, stable, and energy efficient.Advantageously, the active elements may be located near or in directcontact with a flow of molten resin. The active elements may be any of athin film heater, thermistor, thermocouple, resistance temperaturedetector, pressure sensor, gas sensor, optical guide leakage sensor, orcombinations and equivalents thereof. The passive elements, which alsomay be fabricated using thin film technologies, interact with the activeelements and may be made of electrical and thermal insulative materialsand/or wear resistant materials. Preferably, the passive elements are indirect contact with the flow of molten resin to improve the laminar flowthereof. Employing these thin film elements optimizes heat managementand overall control of the injection molding process. In particular, thethin film elements may directly heat the resin in the manifold or hotrunner nozzle according to local and customized needs. Further, the useof thin film elements favorably impacts material selection and componentsize along the melt channel.

[0071] The present embodiments also provide an innovative moldcontroller and logic operation means either coupled to or embedded inthe mold. The mold controller and logic operation means are physicallyindependent from, but in communication with, the controller andmicroprocessor of the injection molding machine. In this regard,reference is made to U.S. Pat. No. 5,320,513 issued to Schmidt, assignedto the assignee of the present invention, and incorporated herein byreference. Schmidt discloses a mold integrated circuit board thatconnects the hot runner nozzle heaters and temperature sensors to themachine controller via a connector. According to the presentembodiments, the printed circuit board of the mold disclosed by Schmidtfurther carries control and logic signals generated by a mold controllerand/or a mold microprocessor. Thus, the end user of the mold will betterbe able to handle the processing parameters of the mold in conjunctionwith various injection molding machines. The mold-machine interface willallow either the mold, the machine, or both to be tuned for specificinjection molding processing conditions. Also, the interface will reducethe complexity of the injection molding controls. Communication betweenthe mold controller and the machine controller and/or between the activethin film elements and the mold controller may be accomplished by eitherwired or wireless means, with the latter further reducing the complexityof the wire connections.

[0072] Mold heat management and process control depend on the specificapplication, the type of resin used, the mold manifold and hot runnernozzle design, and the number of mold cavities. The present embodimentscould be applied to improve heat management and process control inseveral molding processes, three of which processes relate to highcavitation molding and, more particularly, to injection molding ofblowable PET preforms.

[0073] A first application of the present invention reduces and moreuniformly distributes acetaldehyde (“AA”) inherently generated in a moldduring the injection process. European Patent Application 293 756 A2 byHalar, et al., filed by the assignee of the present invention andincorporated herein by reference, thoroughly discusses the problemsassociated with AA formation. According to Halar, et al., a high levelof AA is generated by non-uniform thermal degradation of PET as it flowsthrough manifold channels. This phenomenon is demonstrated in FIGS.1(a), 1(b), and 1(c), in which the velocity profile 20 and the shearstress profile 24 are schematically depicted for the flow of resinthrough a channel 22 of a mold manifold. Due to the melt channel profile26, the resin flows faster at the center of the channel where the shearstress is minimum, thus forming boundary layers that are symmetricalacross the flow. The temperature profile is similar to the shear stressprofile, i.e., the temperature of the resin is minimum at the center ofthe channel. In most molding applications, however, the resin flow doesnot follow a straight path, as shown in FIGS. 1(b) and 1(c), but rathermakes one or more angular turns through a series of branch channels thatsimultaneously feed a plurality of cavity spaces (see FIG. 3). Asindicated in FIG. 1(d), when the resin flow through one channel 21 isdiverted 90 degree into several branches, such as the first two channels27 and 29, the velocity, shear stress, and temperature profiles becomeasymmetrical as the resin flows slower around the inner corner 23 thanthe outer corner 25. At this stage, the shear stress and temperaturevalues 30 are higher near the inner corner 23 than the values 28 nearthe outer corner 25. This asymmetrical behavior further is enhanced andreduced respectively when the flow again is diverted into channels 31and 33. Not only are shear stress and temperature profiles 32 and 36asymmetrical but they are also different from one another.

[0074] Halar, et al. teaches that different asymmetrical profiles indifferent melt channels of a high cavitation mold cause AA differencesin molded parisons. According to Halar, et al., the AA level can beminimized and made more uniform by providing static mixers within themelt channels of the mold manifold. Unfortunately, however, the staticmixers induce a pressure drop and an increase in shear stress. U.S. Pat.No. 5,421,715 issued to Hofstetter, et al. discloses the use of staticmetallic elements called spokes in the manifold channels to createturbulence and homogenize the temperature distribution across the flow,thus reducing the AA level. The spokes of Hofstetter, et al. are nodifferent than the static mixer of Halar, et al. and thus do notrepresent the ideal solution. In summary, providing mechanicalobstructions within the melt channel may more uniformly redistribute theAA level among the injection cavities, but doing so creates additionalproblems.

[0075] A second application of the present invention promotes moreuniform filling of high cavitation molds by suppressing the thermal andviscosity boundary layers that typically form when a flow abruptlychanges direction. FIGS. 2(a) and 2(b) depict the temperature versusviscosity and shear rate versus viscosity graphs for a typical moltenresin. As shown in FIGS. 2(c) and 2(d), an inner layer 40 is hotter andmoves at a slower velocity than the middle and outer layers. If amanifold feeds several cavities, as shown in FIG. 3, the formation ofboundary layers will cause asymmetrical temperature, shear stress, andvelocity profiles for the flow of resin for each cavity, as shown inFIGS. 4(a) and 4(b). This problem, also mentioned by Halar, et al., maybe solved by using a “melt flow-redistributor” such as that disclosed inco-pending U.S. patent application Ser. No. 08/570,333 by Deardurff, etal., assigned to the assignee of the current invention and incorporatedherein by reference. The “melt flow redistributor” is located after a 90degree turn in a melt channel. Thus positioned, this device redirectsthe outer boundary layer of resin, which is more thermally degraded thatthe central layer, in a balanced proportion among several melt channels.Because this device works differently than a static mixer, it does notinduce a pressure drop. However, the “melt flow redistributor” isrelatively difficult to assemble and service.

[0076] A third application of the present invention, derived from thesecond application, combats a phenomenon known as dip. The dip is anuneven or unfilled portion within a co injected layer. FIG. 5illustrates the dip phenomenon occurring in a typical three-material(A-B-C) five-layer (A1-A2-B1-B2-C) PET preform 46. A dip of length Lappears in the neck portion N of the preform 46. Three resins A-B-C areeither sequentially or simultaneously co injected using conventionalinjection means to form a five-layer blowable preform. The dip isunacceptable because one resin (usually the barrier) does not fully fillthe space in the neck area partially occupied by the other resin(virgin, etc.). The dip is believed to be caused by the formation ofboundary layers within a manifold. These boundary layers causenon-uniform temperature and viscosity profiles across a flow of moltenresin, which in turn causes dip. The dip may be improved by providingstatic mixers within the melt channels, but as mentioned previously,such static mixers create additional problems.

[0077] The present invention overcomes the AA, non-uniform filling, anddip problems by replacing or supplementing conventional coil or bandheaters with film heaters strategically disposed along the melt channelsand individually controlled to provide the desired heat profile. Forexample, thin film heaters placed adjacent to each corner 23 can becontrolled to provide more heat to the resin flow than thin film heatersplaced adjacent zone 22 of the melt channels in order to provide aconstant temperature profile throughout the melt channel. Thus located,the thin film heaters can change the velocity, temperature, and shearstress profiles of the flowing resin according to the specific geometryof each melt channel and angle of intersection with adjoining meltchannels.

[0078] A fourth application of the present invention relates to variousimprovements of current injection molding components that, in mostinstances, do not provide an optimum temperature profile in a flowbefore the molten resin enters the mold cavity space. Examples of suchcomponents that would benefit from application of the present inventioninclude coinjection hot runner nozzles, edge gating nozzles, tips ofinjection nozzles, nozzle-manifold interfaces, rim gating nozzles, moldgate inserts, etc.

[0079] Improved components embodying film heaters and insulation layerswill now be discussed with reference to several U.S. patents, each ofwhich is assigned to the assignee of the present invention andincorporated herein by reference.

[0080]FIG. 6 is a schematic cross section showing a high cavitation moldsprue bushing 62, manifold 64, and hot runner nozzles 66 which areheated using thin film heaters 63, 65, and 67, respectively. Each thinfilm heater comprises an active film made of a thin film, electricallyconductive material sandwiched between assorted passive thin filmmaterials. If the thin film heater is internally located so as todirectly contact the molten resin, the thin film heater 62 may comprise(as shown in FIG. 7(a)), in order starting from the channel, a wearresistive film 72, an electrically insulative film 74, the electricallyresistive heater film 76, another layer of electrically insulative film78, and finally a thermally insulative film 79. If the thin film heater65 is externally located (as shown in FIG. 7(b)), the wear resistivefilm may be omitted. Likewise, in some applications the thermallyinsulative film may be omitted.

[0081]FIG. 8(a) shows an improved design of an injection mold in whichthe manifold 80, manifold bushing 82, and hot runner nozzle 84 areindividually heated using thin film electrical heaters 81, 83, and 85,respectively. Because a thin film heater 87 may be located inside thenozzle body and in contact with the molten resin, no temperature dropoccurs in the upper portion A of the hot runner nozzle, as shown by thebroken line in FIG. 8(b).

[0082]FIG. 9 shows an improved design of a hot runner nozzle tip inaccordance with an embodiment of the present invention. Active andpassive thin film elements are located inside the hot runner nozzle body90 along the melt channel 92 and in close proximity to the mold gatearea 94. The active thin film elements are heaters 91, 93, 95, and 97for maintaining the resin at an optimum temperature. Apart fromcompactness and energy savings, the thin film heaters confer severalother significant advantages. For example, the thin film heaters areeasy to locate in areas that are not accessible to coil heaters, such asin the immediate vicinity of the mold gate.

[0083] In the illustrated embodiment, the thin film heaters 95 arelocated along diverter channels of the nozzle tip. The thin film heaters97 may also be located on the inner periphery of the mold gate insert 98in order to heat the mold gate more effectively. Locating thin filmheaters within the mold gate insert provides additional advantages withrespect to “color change” preparation. As is generally known in the art,when changing resins to mold an identical piece but of a differentcolor, one should “flush” the first resin from the nozzle channels. Bylocating a thin film heater 97 on the inner periphery of the mold gateinsert, the insert may be heated to facilitate flushing of the gatechannel. Also, heaters may be combined with thermocouples as shown at 97and 99.

[0084] The mold gate insert further may comprise a thin film pressuresensor 96 and/or thin film temperature sensors (not shown). FIG. 10shows the disposition of pressure sensors 96 and thermocouple 100 aroundthe nozzle tip 90 degree. As shown in FIG. 11, the individual componentsof the hot runner nozzle and mold gate insert are easily removed,manufactured, and serviced.

[0085]FIG. 12 shows a coinjection nozzle with thin film heaters inaccordance with yet another embodiment of the present invention. Atleast one thin film heater may be disposed around or inside the housingof each coinjection channel to better control the temperature of eachresin. In this embodiment, a three channel nozzle is shown wherein thechannel 110 carries resin A, channel 112 carries resin B, and channel114 carries resin C. The valve gate stem 116 selectively shuts offcommunication between the nozzle channels and a cavity space 118. Thinfilm heaters 111, 113, and 115 are respectively located inside thechannels. However, for certain applications it may be possible to useonly two heaters, with one heater heating two channels if the wallbetween the two channels is thin and/or thermally conductive. Forexample, in FIG. 11 heater 111 may be sufficient to heat both resins Aand B. Because the thin film heaters will directly contact the flow ofmolten resin, a wear resistive film may be provided directly adjacent tothe flow.

[0086]FIG. 13 shows a molding machine including shooting pots 120 formetering the amount of resin delivered to the hot runner nozzle 122.Shooting pots are typically used when injecting parts that must meetstringent weight requirements, such as the accurately measured layerscommonly required for a coinjection mold. In accordance with the presentinvention, thin film heaters 121 is located in the shooting pot area toheat the shooting pot area independently from other thin film manifoldheaters such as heaters 123, 125 disposed on manifold 124. Additionally,thin film thermal sensors may be located in the shooting pot area.

[0087] FIGS. 14(a) and 14(b) show preferred means for removablyattaching a thin film heater to either the outside or the inside of ahot runner nozzle, respectively. The thin film heater is deposited on aflexible thin, band substrate that may display spring-likecharacteristics. A thin firm heater attached in this manner may beeasily replaced in the event of a failure. In FIG. 14(a), think firmheater 132 is disposed outside of nozzle ′30 and may comprise, forexample, electrically insulated layer 132, electrically conductive layer134, and electrically insulated layer 136. A connector 138 fits within achannel of the nozzle 130 and restrains the two ends of the resilientheater 132. Such construction can provide localized heat to the resinand melt channel 139. In FIG. 14(b), the heater 132 is disposed insidenozzle 130 and may also comprise the layers 132,134, and 136. A warlayer (now shown) can also be provided between layer 132 and the meltchannel 139 to present wear on the heater 132. Of course, the heatingelements in layer 134 may extend only partially around the circumferenceof the nozzle, and be in any configuration (spiral, planar, stripped,herringbone, annular, etc.). Also, the heating elements may extend todifferent lengths along the axial direction of the nozzle.

[0088]FIG. 15 shows an injection molding machine having both a hotrunner valve gate and a hot runner thermal gate. The molten resinprecedes from the machine injection nozzle (not shown) through the spruebushing 150 into the manifold 152 and into the melt channel of eachnozzle. The molten resin flowing through the bushing and manifold may bemaintained at the optimum temperature by using well known band or coilelectric heaters. The molten resin is then injected through each of thenozzles into respective mold cavities 154 and 156. The hot runner valvegate 158 has a thin film heater 159 associated therewith to maintain themolten resin at the precise, desired temperature as it passes throughthe valve gate 158 into the cavity 154. Likewise, the hot runner thermalgate 157 has a thin film heater 155 associated therewith to preciselycontrol the temperature of the molten resin as it flows into cavity 156.

[0089]FIG. 16(a) is a schematic cross-section of a valve gated hotrunner nozzle where a film heater is deposited directly on the tipportion of the stem, and a film thermocouple is deposited directly onthe end of the stem. The valve-gated nozzle 160 has a nozzle tip 162which fits within mold plate 164 abutting the mold plate 164′ containingthe mold cavity space 166. The movable valve stem 168 has a film heater167 deposited on the outer surface thereof in a pattern, for example, asshown in FIG. 16(a). Preferably, and as shown in FIG. 16(b), athermocouple is deposited on the end of valve stem 168 for accuratetemperature measurement precisely at the valve gate itself.

[0090] As shown schematically in FIG. 16(a), the film heater 167 may becoupled to electrical contacts 161 through terminals 163. Likewise,electrical contacts 165 are disposed to contact terminals 169. Theelectrical contacts are coupled to a mold control processor 1000, suchas that described in the Schmidt patent discussed above.

[0091]FIG. 17 is a cross-sectional view of the film heater 167 of FIG.16(a). Closest to the valve stem 168 is a layer 171 made of electricalinsulative material. Next is a layer 173 which comprises theelectrically resistive material forming the heating element. On theoutside is layer 175 which comprises an electrically insulative materialthat also has good thermal transmission characteristics.

[0092]FIG. 18(a) is a schematic cross-sectional drawing showing filmheater 181 disposed on a bottom exterior surface of nozzle tip 180. Asshown in FIG. 18(b), the film heater 181 may have a resistive patternwhich surrounds the melt channels 182 and 183, as shown. The heaterterminals 184 and 184′ may be connected to electrical contacts (notshown).

[0093] The nozzle tip 180 may also have a heater plug 190 (to bedescribed below) which has a film heater 191 disposed on an outersurface thereof. The heater plug 190 is disposed in the melt channel 186of the nozzle tip 180. Both film temperature sensors (not shown), mayalso be deposited on any convenient surface of the nozzle tip 180 tomonitor the temperature of the molten resin in the melt channel 186.Preferably, the temperature sensor is a film thermocouple disposed indirect contact with the molten resin very close to the mold gateorifice.

[0094] Preferably, the nozzle tip 180 includes electrical connectors forthe thermocouple and the heater which are attached to the nozzle body bya fast removal mechanism, such as a bayonet mechanism, which allowsrapid assembly and removal of the tip without having to disconnect anywiring. In some instances, it is preferable to have two thermocouplesplaced close to each other so that if one is broken, the other one isstill operative.

[0095]FIG. 19(a) is a schematic cross-section of a film heater plug 190which is a convenient and easy way to apply film heaters and filmsensors to the melt channels of injection molding machines. Plug 190comprises a metal plug 192 having a film heater 193 disposed on aninterior surface thereof adjacent the melt channel 194. Preferably, theheater 193 comprises an inner wear resistive layer 195, an electricallyresistive layer 196, an electrical insulation layer 196, and a thermalinsulation layer 198. The advantage of such a construction is that theplug 190 can be made small and replaceably positioned at any point inthe melt channel. The plug can be used at any located in alignment withthe melt channel of the mold, for example, in the manifold, in the hotrunner housing or in the nozzle tip. The melt channel can be constructedcomplementary structure so that such heater plugs can be placed at anyconvenient location along the melt channel. Moreover, such plugs can belinear, T-shaped, or angled to fit any location along the melt channel.Since it is much easier to dispose a flexible film heater on theinterior surface of a small, replaceable heater plug, the cost ofdisposing that heaters on the inside surface of a long melt channelmanifold (as depicted in FIG. 3) can be avoided.

[0096]FIG. 19(b) depicts another embodiment of the heater plug 190 inwhich the heater 193 is disposed on the outer surface 192. In thisinstance, the inner layer 195′ comprises a dielectric with good thermaltransmitting characteristics, layer 196′ is the electrically resistiveheating element, and layer 197′ is a thermal insulator. In someinstances, a wear resistant layer may be deposited on the outside of thelayer 197′. Likewise, a wear resistant layer 198′ may be deposited onthe inside of the plug 192 to enhance resistant to the wear of themolten resin.

[0097]FIG. 20 shows the application of removable heater plugs 201 and202 within an injection molding machine. Heater plug 201 has film heater203 on the exterior surface thereof and is disposed within manifold 204,which, for example, may also be heated by conventional manifold heater205.

[0098] The heater plug 202 is disposed within nozzle head 206 and nozzlebody 207 and has a wear resistant layer (sleeve) 208 disposed on aninterior surface thereof adjacent the melt channel 209. A film heater210 is disposed on an exterior surface of the heater plug 202 adjacentthe nozzle tip 211. The nozzle housing 212 is preferably made of athermal insulation material. The heater plugs 201 and 202 are preferablymade of a highly thermally conductive material such as CuBe. Since theheater plugs 201 and 202 are modular and removable, they may be easilyreplaced for repair or for the molding of different types of plasticresin.

[0099]FIG. 21(a) is a schematic cross-section of a mold gate insert 210having an internal film heater 211 disposed on an inside surfaceadjacent the nozzle tip (not shown) and the mold gate orifice 212. Sincethe mold gate insert 210 is removable, a connector 213 is disposed on asurface thereof to carry the electrical contact wires to the film heater211. The connector 213 will mate with a like connector in the nozzlehousing or the mold plate (not shown) so that the entire mold gateinsert 210 is quickly and easily replaceable.

[0100]FIG. 22(b) is a schematic cross-section of a mold gate sleeve 215wherein the mold gate body 216 has a film heater 217 disposed on the oneor more of the outer surfaces thereof. Again, since the mold gate sleeveis easily replaceable, it is simple to replace a defective heater or tochange the heating capacity of the heater for different types of resin.

[0101]FIG. 22 is a schematic cross-section of a heater plug 220 having afilm heater disposed on the outer surface thereof; however, the filmheater layer has different thicknesses in areas A, B, and C to providean engineered temperature profile, as depicted in the left-hand portionof FIG. 22. This may be used, for example, in molding applications whereportions A and C are located adjacent mold plates which are cooledduring the molding process. This way, the molten resin flowing withinthe melt channel 222 will be maintained at a constant temperature. Notethat in this embodiment, a high wear resistive sleeve 223 is disposed onthe interior surface of the heater plug 220.

[0102]FIG. 23 (a) is a schematic view of a thin film heater according tothe present invention having two rectangular patterns of heatingelements. Heater 231 has an element with a length L and a pitch P1.Heater 232 has a heating element with the same length L, but with adifferent pitch P2. Thus, the same thin film element may providedifferent heating characteristics to contiguous areas of the meltchannel. The contact terminals have a length Lt and a width T adapted toeasily engage electrical contacts on the melt channel structure wherethe heater is to be mounted.

[0103]FIG. 23(b) is a schematic of a heater having a serpentine shapedheating element 235 with contact terminals at different ends thereof.

[0104]FIG. 23(c) shows a film heater bent so as to be disposed on theinside of a melt channel, and FIG. 23(d) shows such a heater bent on theoutside of a melt channel.

[0105] The following materials, deposition technologies, and patterningmethods are recommended for the various layers used to manufacture thecompound film heater deposited directly on the mold elements or on afilm heater plug (the thickness of these layers varies from less than 5microns and up to 2-3 millimeters):

[0106] electrical resistive materials: TiN; tungsten, molybdenum, gold,platinum, copper, TiC, TiCN, TiAIN, CrN, palladium, iridium, silver,conductive inks;

[0107] electrical insulative materials: beryllium oxide; see also thematerials disclosed in the U.S. Pat. No. 5,653,932 and U.S. Pat. No.5,468,141 both herein incorporated by reference;

[0108] wear resistance materials: titanium, titanium alloys, chrome,electroless nickel, also see the materials disclosed in the U.S. Pat.No. 5,112,025 herein incorporated by reference;

[0109] deposition technologies: ion plating, sputtering, chemical vapordeposition (CVD), physical vapor deposition (PVD), flame spraying; and

[0110] film patterning methods: etching through a mask; laser removal;wire masking, mechanical removal.

[0111] Example for the heat requirement:

[0112] Wattage Density 40-80 W/square inch at 240 V;

[0113] See FIG. 13;

[0114] Zone A: 37 mm 150 W (tip);

[0115] Zone B: 75 mm 50 W (center);

[0116] Zone C: 34 mm 100 W (head);

[0117] One or several heaters;

[0118] Patterning: laser removal; lathe; mask wire, etching;

[0119] Deposition: sputtering;

[0120] Materials: platinum, tungsten, Molybdenum; and

[0121] Film sensors for molding applications.

[0122] Film temperature sensing elements have been disclosed in, forexample, U.S. Pat. No. 5,215,597 issued to Kreider, U.S. Pat. No.5,573,335 issued to Schinazi, NASA Report E-7574 of February 1993 by R.Holanda and NASA Report E-9080 of August 1994 by L. C. Martin et al.,all of which are all incorporated herein by reference.

[0123] Any film temperature sensing device, such as thermistors, othersemi-conductor based devices, or resistance temperature detectors (RTD)are encompassed by the scope of the current invention. Reference is madein this regard to U.S. Pat. No. 4,968,964 issued to Nagai et al., andthe Platinum Resistance Temperature Detector (P-RTD) Catalogs of Heraeusthat are incorporated herein by reference. The current invention alsoencompasses a thin film RTD as another preferable alternative to a filmthermocouple, because it offers the advantage of being made of a singlethin film material that is easier to deposit and etched.

[0124] According to the current invention, it is preferable to selectthe materials for the film thermocouple that meet the currentthermocouple standards (such as ANSI), and that can be deposited on thesupport base of the mold part. Accordingly, a major design target forthe film thermocouple is to select two dissimilar materials for thewires that are either identical or close to the resistive material ofthe thin film heater.

[0125] The following commercial data published by Insulation Seal Inc.and SRS Corp. show the material selection and characteristics forseveral standard thermocouples that can be also used as guidelines tomanufacture film thermocouples. ANS I Thermocouple Pair TC TemperatureMedium Std. Type Materials & Polarity (max.) Error T Copper (+)  350° C.Constantan (−) J Iron (+)  750° C. +/−2.2° C. Constantan (−) E Chromel(+)  900° C. +/−1.7° C. Constantan (−) K Chromel (+) 1250° C. +/−2.2° C.Alumel (−) R Platinum 13% Rhodium (+) 1450° C. +/−1.4° C. Platinum (−) SPlatinum 10% Rhodium (+) 1450° C. +/−1.4° C. Platinum (−) C Tungsten 5%Rhenium (+) 2320° C. Tungsten 26% Rhenium (−) B Platinum 30% Rhodium (+)1700° C. +/−4.4° C. Platinum 6% Rhodium (−)

[0126] According to the current invention, the film thermocouple is madeusing well known microlithographic techniques that insure a very highdimensional accuracy, excellent adhesion of the thermocouple to thesubstrate and connection between the two dissimilar materials. Anotheradvantage of the microlithographic technique is that a batch ofthermocouples can be simultaneously manufactured in order to ensure thatthe thickness of the deposited alloy is the same for several temperaturesensing elements that will be mounted in a high cavitation mold. Anotheradvantage is that, with no extra cost and within the same space, a “backup” or a reference thermocouple can be actually deposited close to theactual thermocouple. In this manner, if for whatever reason the currentthermocouple fails to respond, the back up can be activated, withoutinterrupting the molding process or servicing the mold.

[0127] In a preferred embodiment, a thin film (R-class) thermocouple ismade of Platinum-13% Rhodium and Platinum and is manufactured in a class1000 Clean Room using the well known sputtering process. Depending onthe location of the thin film wires to the lead wires connections aremade using the well known parallel-gap welding process. Thisthermocouple can be located anywhere along the melt channel as it canwithstand temperatures in excess of 1,000 degree C.

[0128] Thus, what has been described is unique structure and functionwhereby heating, sensing, and melt control in a molding machine may besimplified, made easy to replace, and may be customized and to providemolded articles more quickly, less expensively, and with higher quality.

[0129] While the present invention has been described with respect towhat are presently considered to be the preferred embodiments, it is tobe understood that the invention is not limited to the disclosedembodiments. To the contrary, the invention is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims. The scope of the following claims is to beaccorded the broadest interpretation so as to encompass all suchmodifications and equivalent structures and functions.

1-49. (Cancelled)
 50. A film heater for heating a melt channel in amolding apparatus, the heater comprising: a heat conducting substrate; afirst dielectric layer on a surface of said substrate; an active heatingelement on said first dielectric layer, said active heating elementbeing configured to cause heating through said heat conductingsubstrate, said active heating element having contact terminalsconfigured to support an electrical connection to said active heatingelement; and a second dielectric layer extending over said activeheating element, but not covering the contact terminals, so that thecontact terminals are configured to couple the active heating element toan electrical supply.
 51. A heater according to claim 50, wherein saidactive heating element is disposed in a spiral pattern.
 52. A heateraccording to any one of claims 50 and 51, wherein said second dielectriclayer comprises an electrically insulating and mechanically protectivelayer.
 53. A heater according to any one of claims 50 and 51, whereinsaid active heating element is selected from the group consisting of aconductive-ink, a thin film, and a resistive material.
 54. A heateraccording to claim 53 wherein said resistive material is selected fromthe group consisting of TiN, Tungsten, Molybdenum, Gold, Platinum,Copper, TiC, TiZCN, TiAIN, Crn, Palladium, Iridium, and Silver.
 55. Aheater according to any one of claims 50 and 51, wherein said heatconducting substrate is cylindrical with spring like characteristics.56. A heater according to any one of claims 50 and 51, wherein saidactive heating element comprises a layer having a plurality ofthicknesses configured to provide a temperature profile within saidheater.
 57. A heater according to any one of claims 50 and 51, whereinsaid active heating element comprises a plurality of contiguous filmelements having different pitches configured to provide differentheating characteristics.
 58. A heater according to any one of claims 50and 51, further comprising a passive electrical element.
 59. A heateraccording to claim 58, wherein said passive electrical element isselected from the group consisting of a pressure sensor, a temperaturesensor, a gas sensor, and a leakage sensor.
 60. A heater according toclaim 50, wherein said active heating element comprises two heatingelements coupled to each other and configured to be coupled betweenelectrical contacts, said two heating elements being disposed in apattern about a circumference of said dielectric layer, and wherein saidpattern comprises at least one of a spiral pattern, a planar pattern, astriped pattern, a herringbone pattern, and an annular pattern.
 61. Aheater according to claim 50, wherein said second dielectric layercomprises an insulative layer.
 62. A heater according to claim 61,wherein said insulative layer comprises a thermal insulation layer. 63.A heater according to claim 50, further comprising a wear resistantlayer adjacent said second dielectric layer.
 64. A heater according toclaim 50, wherein said heat conducting substrate comprises a removableplug configured to be positionable about said melt channel.
 65. A heateraccording to claim 50, wherein said heat conducting substrate comprisesan inner surface of the melt channel.
 66. A heater according to claim50, wherein said heat conducting substrate is configured to be disposedexternal to the melt channel.
 67. A molding apparatus comprising; amold; at least one melt channel, said at least one melt channel beingdisposed in said mold; at least one film heater configured to heat aportion of said at least one melt channel; and a heat conductingsubstrate, said heat conducting substrate being disposed substantiallyadjacent said at least one melt channel, said at lease one film heatercomprising: a first dielectric on a surface of said substrate; an activeheating element on said first dielectric layer, said active heatingelement being configured to cause heating through said heat conductingsubstrate, said active heating element having contact terminalsconfigured to support an electrical connection to said active heatingelement; and a second dielectric layer extending over said activeheating element, but not covering the contact terminals, so that saidcontact terminals are configured for coupling said heater element to anelectrical supply.
 68. An molding apparatus comprising; a stationaryportion of a mold; at least one melt channel, said at least one meltchannel being disposed in said stationary portion; at least one filmheater configured to heat a portion of said at least one melt channel;and a heat conducting substrate, said heat conducting substrate beingdisposed substantially adjacent the at least one melt channel; said atleast one film heater comprising: a first dielectric on a surface ofsaid substrate; an active heating element on said first dielectriclayer, said active heating element being configured to cause heatingthrough said heat conducting substrate; said active heating elementhaving contact terminals configured to support an electrical connectionto said active heating element; and a second dielectric layer extendingover said active heating element, but not covering the contactterminals, so that said contact terminals are coupleable to anelectrical supply.
 69. A molding apparatus comprising; a hot runner; atleast one melt channel disposed in said hot runner; at least one filmheater configured to heat a portion of said at least one melt channel;and a heat conducting substrate, said at least one heat conductingsubstrate being disposed substantially adjacent the at least one meltchannel; said at lease one film heater comprising: a first dielectricconfigured to be disposed on a surface of said substrate; an activeheating element configured to be disposed on said first dielectriclayer, said active heating element being configured to cause heatingthrough said heat conducting substrate; said active heating elementhaving contact terminals configured to support an electrical connectionto said active heating element; and a second dielectric layer extendingover said active heating element, but not covering the contactterminals, to cause said contact terminals to be coupleable to anelectrical supply.
 70. A molding apparatus comprising; a manifold; atleast one melt channel configured to be disposed in said manifold; atleast one film heater configured to heat a portion of said at least onemelt channel; and a heat conducting substrate configured to be disposedsubstantially adjacent said at least one melt channel; said at lease onefilm heater comprising: a first dielectric disposed on a surface of saidsubstrate; an active heating element disposed on said first dielectriclayer, said active heating element being configured to cause heatingthrough said heat conducting substrate, said active heating elementhaving contact terminals configured to provide an electrical connectionto said active heating element; and a second dielectric layer disposedover said active heating element, but not covering the contactterminals, so that said contact terminals are coupleable to anelectrical supply.
 71. A molding apparatus comprising; a nozzle; atleast one melt channel disposed in said nozzle; at least one film heaterconfigured to heat a portion of said at least one melt channel; and aheat conducting substrate disposed substantially adjacent said at leastone melt channel, said at lease one film heater comprising: a firstdielectric on a surface of said substrate; an active heating element onsaid first dielectric layer, said active heating element configured tocause heating through said heat conducting substrate, said activeheating element having contact terminals configured to provide anelectrical connection to said active heating element; and a seconddielectric layer extending over said active heating element, but notcovering the contact terminals, to cause the contact terminals to beconfigured for connection to an electrical supply.
 72. A moldingapparatus comprising; a gate insert; at least one melt channel disposedin said gate insert; at least one film heater configured to heat aportion of said at least one melt channel; and a heat conductingsubstrate disposed substantially adjacent said at least one meltchannel; said at lease one film heater comprising: a first dielectric ona surface of said substrate; an active heating element on said firstdielectric layer, said active heating element configured to causeheating through said heat conducting substrate, said active heatingelement having contact terminals configured to provide an electricalconnection to said active heating element; and a second dielectric layerextending over said active heating element, but not covering the contactterminals, so that the contact terminals are coupleable to an electricalsupply.
 73. An apparatus as in any one of claims 67, 68, 69, 70, 71, and72, wherein said active heating element is selected from the groupconsisting of conductive-ink, thin film, and resistive material.
 74. Anapparatus as in any one of claims 67, 68, 69, 70, 71, and 72, whereinsaid resistive material is selected from the group consisting of TiN,Tungsten, Molybdenum, Gold, Platinum, Copper, TiC, TiZcn, TiAIN, Crn,Palladium, Iridium, and Silver.
 75. An apparatus as in any one of claims67, 68, 69, 70, 71, and 72, further comprising a passive electricalelement selected from the group consisting of a pressure sensor, atemperature sensor, a gas sensor, and a leakage sensor.
 76. An apparatusas in any one of claims 67, 68, 69, 70, 71, and 72, wherein saidconducting substrate comprises a removable plug configured to bepositionable about said melt channel.
 77. An apparatus as in any one ofclaims 67, 68, 69, 70, 71, and 72, wherein said conducting substratecomprises an inner surface of said melt channel.
 78. An apparatus as inany one of claims 67, 68, 69, 70, 71, and 72, wherein said conductingsubstrate is external to said melt channel.
 79. A method of providingheat to a plastic resin flowing through a molding melt channel definedby a surface, the method comprising the steps of: securing a heateraccording to one of claims 67, 68, 69, 70, 71, and 72 in a mold; andsupplying electrical energy to the heater to generate heat in saidactive heating element for conduction to said plastic resin in said meltchannel.
 80. A method of manufacturing a molding film heater, comprisingthe steps of: forming a first dielectric layer on a surface of asubstrate; depositing an active heating element in a predefined patternon said first dielectric layer, said depositing step being selected fromamong a group of steps consisting of ion plating, sputtering, chemicalvapor deposition, physical vapor deposition, and flame spraying; andforming a second dielectric layer over said active heating element butnot covering the contact terminals, thereby permitting, coupling of theheater element to an electrical supply.
 81. The method of manufacturingaccording to claim 80, further comprising the step of patterning saidactive heating element to form a conductive pattern on said firstdielectric layer, said patterning step being selected from among thegroup of steps consisting of etching through a mask, laser removal, wiremasking, and mechanical removal.
 82. An injection molding machineapparatus comprising: a cavity plate; a core plate disposed relative tothe cavity plate so that the core plate and cavity plate together form acavity space; a manifold having formed therein an inlet passage forreceiving a flow of molten resin from a nozzle of the injection moldingmachine; a hot runner nozzle for directing the flow of molten resin fromthe manifold inlet passage to the cavity space; a mold gate forregulating the flow of molten resin from the hot runner nozzle to thecavity space, the mold gate together with the hot runner nozzle and themanifold inlet passage defining a non-flat melt channel for directingthe flow of molten resin from the nozzle of the injection moldingmachine to the cavity space; and an active or passive film elementdisposed along the non-flat melt channel.
 83. An injection moldingapparatus comprising: a mold defining a cavity space; a manifold havingformed therein an inlet passage for flow communication with a nozzle ofthe injection molding machine; a hot runner nozzle for flowcommunication with each of the cavity space and the manifold inletpassage, the hot runner nozzle and the manifold inlet passage togetherdefining a melt channel; and a plurality of active or passive filmelements intermittently disposed along the melt channel.
 84. Anapparatus for directing a flow of molten resin supplied by an injectionmolding machine to a cavity space defined by a mold, the apparatuscomprising: a hot runner nozzle including a plurality of melt channelsfor directing the flow of molten resin supplied by the injection moldingmachine to the cavity space; and a plurality of active or passive filmelements disposed substantially adjacent to each melt channel, saidactive film elements for supplying heat to the flow of molten resinwithin that melt channel or said active film elements for sensing amolding condition.
 85. An injection apparatus to form molded articles ina mold cavity, comprising: a mold manifold having a plurality ofconduits to guide a molten material toward the mold cavity; a firstelectrical film heater located adjacent at least one of the conduits tomaintain the molten material in a predetermined molding temperaturerange; a nozzle coupled to said mold manifold and having at least onenozzle conduit to guide said molten material toward the mold cavity; asecond electrical film heater located adjacent said nozzle conduit tomaintain the molten material within the predetermined molten temperaturerange; a nozzle tip coupled to the nozzle and having at least one tipconduit in fluid communication with the nozzle conduit; a mold gate influid communication with the nozzle tip conduit and with the moldcavity; wherein at least one of said first and second electrical filmheaters includes (i) an insulation layer in contact with said at leastone of the conduits and the nozzle conduit, and (ii) an electricallyresistive layer disposed on said insulation layer and having a thicknessof less than substantially 0.5 mn.